It is known that well "oxygenated" cells are more sensitive to radiation, and that anoxia reduces radiosentitivity of cells. Tumoral cells often are poorly "oxygenated," and therefore are not very sensitive to therapeutic radiations.
Hyperbaric oxygen therapy makes it possible to increase oxygenation of tumoral cells and consequently to make them more vulnerable to radiation, and thus to improve the effectiveness of a therapeutic irradiation. Therefore, a therapy combining radiotherapy and hyperbaric oxygen therapy has been developed, according to which the patient is placed under oxygen in a single-person hyperbaric chamber transparent to radiation and placed under a radiation generator (X or gamma-cobalt).
The development of this therapy is slowed down by the cost and awkwardness of implementation and of the equipment required: hyperbaric chamber, protocol and remote monitoring of the patient placed in the chamber and under irradiation, compression and decompression process, safety precautions because of the use of pure oxygen in the chamber, etc.
To increase the oxygenation of the cells without using hyperbaric oxygen therapy, "normobaric" oxygen therapy was proposed. This therapy comprising in inhalation by the patient at ambient pressure of superoxygenated air, even of pure oxygen, already represented a first improvement, but makes it possible to increase only slightly the amount of oxygen available in the blood and tissues.
Also, a more effective means of radiosentitizing the cells to be treated by radiotherapy was sought.